Insect Abundance - Sticky Traps

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In use from 2019-05-01

Abstract

The spatial and temporal dynamics of adult flying insects that provide herbivore suppression in the families Coccinellidae, Chrysopidae, Lampyridae, and Cantharidae are monitored across the KBS LTER site using sticky traps. Traps consist of a double-sided yellow cardboard with an un-baited sticky coating and are suspended from a pole 1.2 m above the ground. These traps have the advantages of being simple to maintain, low cost, suitable for a variety of habitats, and easy to remove for agronomic practices; this allows for sampling of many locations over a large area.

Sticky traps are monitored weekly during the growing season. Adults of species of interest that collect on the sticky traps are identified in the field using a pictorial key, counted, recorded on sampling sheets, and then removed from the card. Traps are replaced every two weeks. Species new to sticky trap collections are preserved in ethanol for later identification and are included in future predator counts (e.g. new species records, invasive species). Data and ancillary information are entered in a statistical spreadsheet for analysis and archiving.

For the Main Cropping System Experiment (MCSE), abundances are monitored weekly throughout the growing season (early May to late August) at each of the five permanent sampling stations per replicate in all treatments except in the Mown Grassland Never-tilled treatment (T8). Permanent sampling sites allow monitoring of temporal variation (weeks, years) while accounting for spatial variation. For the MCSE, a total of 255 sampling stations are monitored [(since 1989, 7 treatments at the LTER Main Site x 6 replicates x 5 stations) + (since 1993, 3 successional and forest site x 3 replicates x 5 stations)].

Protocol

Materials

  • Pictorial keys of insects
  • Datasheets, pencils, pens, Sharpie
  • Tweezers
  • Double sided sticky traps with 22.9 × 17.8 cm (9 × 7”) of sticky surface per side, “Corn rootworm trap”, Great Lakes IPM Vestaburg MI
  • Twist ties for hanging traps
  • Metal T-Posts to hang traps from
  • Storage vials containing 70% ethanol

Procedure

Weekly counts:

  1. Scan the sticky trap to get an overall impression of the abundance of species present. Use the pictorial key to assist in identification.
  2. Count the total number of adults of each species (on both sides of the sticky trap) for all species listed on the insect abundance datasheet , record number on the datasheet, and remove each individual from the sticky trap. Species that are not listed on the datasheet (e.g., flies etc.) can be left adhering to the sticky trap.
  3. Collect individuals of unknown or rare species (in the families Coccinellidae, Chrysopidae, Lampyridae, and Cantharidae) that are not listed on the datasheet into a sample vial containing 70% ethanol for preservation and taxonomic identification. Label the vial with date and sampling location.

Trap maintenance:

  1. Replace all sticky traps every two weeks. Secure trap onto the supporting pole using the twist ties provided by the supplier. Replace trap earlier if trap surface has less than 80% sticky surface remaining due to dust or insect accumulation. Also replace traps if they are found on the ground or damaged in any way. Note trap changes on the datasheet.
  2. Remove supporting poles from plots as needed for agronomic procedures. Return poles to respective sampling locations as soon as possible; if poles cannot be replaced immediately, after pesticide treatment for example, be sure to record the number of days that traps were absent on the datasheet.

Data management:

  1. Field Datasheets are collected from field technicians monthly and scanned into PDFs.
  2. Vials with specimens needing expert identification are collected and identified back on campus. The datasheet is updated as new taxa are identified.
  3. Field datasheets are transcribed onto an Excel workbook template and quality checked for errors. For each species on the datasheet, the number (raw count) of adults on the sticky trap is recorded (0, 1, 2, etc.).
  4. The targeted species of interest may be revised if abundances, regularity, and/or research interests warrant. For examples, the column where “Carabids” were previously recorded (but rarely observed ion sticky traps) was replaced with Cantharids in 2018.
  5. The final step is to transfer the data from the Excel workbook into the Database using R Statistical Software.

Date modified: Wednesday, Oct 14 2020

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